Retinal vascular disease is one of the major causes of human visual disability and blindness. Diabetic retinopathy, sickle retinopathy, hypertensive retinopathy, retrolental fibroplasia, and senile macular degeneration are but a few of the disorders of the human retinal vascular system. By retinal vascular, we imply both the intra-retinal vessels and the choroidal vasculature. We utilize a multipronged approach to examine the retinal vessels in health and disease: 1) We perform anatomic and physiologic investigations on the retinal vascular systems of diverse animal species. 2) We make clinico-pathologic correlations of human and animal spontaneous retinal vascular disease. 3) We produce and study experimental models of retinal vascular disease. In our studies we use techniques of clinical observations which include fundus photography and fluorescein angiography; electrophysiology; histology; histochemistry; electron microscopy; and biochemistry.